Ancient Painting on Copper Substrate Inspected by Terahertz Spectroscopy-Imaging

We report on further development of terahertz systems for measuring the thicknesses of multiple films for noncontact control in art science. Analysis of time-domain data is described and the results of measurements made on ancient real painting realized on a copper substrate are presented. We also show X-Ray images and show that we can clearly differentiate the pigments and some sketches are surprisingly revealed under the painting by terahertz imaging.